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Articles 2341 - 2370 of 5700
Full-Text Articles in Engineering
Improvements To Optical Communication Capabilities Achieved Through The Optical Injection Of Semiconductor Lasers, Timothy P. Locke
Improvements To Optical Communication Capabilities Achieved Through The Optical Injection Of Semiconductor Lasers, Timothy P. Locke
Theses and Dissertations
Optically injection locked lasers have shown significant improvement in the modulation capabilities of directly modulated lasers. This research creates a direct-modulated optical communications system to investigate the bit-rate distance improvements achievable using optically injected Fabry-Pérot laser diodes. The injection strength and detuning frequency of the injection signal was varied to determine their impact on the optical communication link's characteristics. This research measured a 25 fold increase in bit-rate distance product using optical injection locking as compared to the injected laser's free-running capability. A 57 fold increase was measured in the bit-rate distance product when signal power is considered in a …
Air-To-Air Missile Enhanced Scoring With Kalman Smoothing, Jonathon S. Gipson
Air-To-Air Missile Enhanced Scoring With Kalman Smoothing, Jonathon S. Gipson
Theses and Dissertations
A correct estimate of a missile's flight path is essential to USAF test and evaluation efforts. The USAF air-to-air Weapons System Evaluation Program (WSEP) targets unmanned aerial drones in hundreds of live-fire missile tests each year. The current QF-4 drone inventory is expected to be depleted by 2015. The QF-16 Full Scale Aerial Target (FSAT) contract has been awarded to convert usable early model F-16s into remote-controlled drones. The QF-16 will provide a highly-maneuverable, realistic testing environment for 5th generation fighters. To accomplish their mission, WSEP requires a scoring system capable of estimating the trajectory of a missile relative to …
Computer Aided Multi-Data Fusion Dismount Modeling, Juan L. Morales
Computer Aided Multi-Data Fusion Dismount Modeling, Juan L. Morales
Theses and Dissertations
Recent research efforts strive to address the growing need for dismount surveillance, dismount tracking and characterization. Current work in this area utilizes hyperspectral and multispectral imaging systems to exploit spectral properties in order to detect areas of exposed skin and clothing characteristics. Because of the large bandwidth and high resolution, hyperspectral imaging systems pose great ability to characterize and detect dismounts. A multi-data dismount modeling system where the development and manipulation of dismount models is a necessity. This thesis demonstrates a computer aided multi-data fused dismount model, which facilitates studies of dismount detection, characterization and identification. The system is created …
Near Earth Object Detection Using A Poisson Statistical Model For Detection On Images Modeled From The Panoramic Survey Telescope And Rapid Response System, Curtis J. R. Peterson
Near Earth Object Detection Using A Poisson Statistical Model For Detection On Images Modeled From The Panoramic Survey Telescope And Rapid Response System, Curtis J. R. Peterson
Theses and Dissertations
The purpose of this research effort is to develop, simulate, and test a new algorithm to detect Near Earth Objects (NEOs) using a Likelihood Ratio Test (LRT) based on a Poisson statistical model for the arrival of photons. One detection algorithm currently in use is based on a Gaussian approximation of the arrival of photons, and is compared to the proposed Poisson model. The research includes three key components. The first is a quantitative analysis of the performance of both algorithms. The second is a system model for simulating detection statistics. The last component is a collection of measured data …
All Source Sensor Integration Using An Extended Kalman Filter, Timothy R. Penn
All Source Sensor Integration Using An Extended Kalman Filter, Timothy R. Penn
Theses and Dissertations
The global positioning system (GPS) has become an ubiquitous source for navigation in the modern age, especially since the removal of selective availability at the beginning of this century. The utility of the GPS is unmatched, however GPS is not available in all environments. Heavy reliance on GPS for navigation makes the warfighter increasingly vulnerability as modern warfare continues to evolve. This research provides a method for incorporating measurements from a massive variety of sensors to mitigate GPS dependence. The result is the integration of sensor sets that encompass those examined in recent literature as well as some custom navigation …
Covariance Analysis Of Vision Aided Navigation By Bootstrapping, Andrew L. Relyea
Covariance Analysis Of Vision Aided Navigation By Bootstrapping, Andrew L. Relyea
Theses and Dissertations
Inertial Navigation System (INS) aiding using bearing measurements taken over time of stationary ground features is investigated. A cross country flight, in two and three dimensional space, is considered, as well as a vertical drop in three dimensional space. The objective is to quantify the temporal development of the uncertainty in the navigation states of an aircraft INS which is aided by taking bearing measurements of ground objects which have been geolocated using ownship position. It is shown that during wings level flight at constant speed and a fixed altitude, an aircraft that tracks ground objects and over time sequentially …
Electromagnetic Characterization Of Inhomogeneous Media, Marcus A. Sitterly
Electromagnetic Characterization Of Inhomogeneous Media, Marcus A. Sitterly
Theses and Dissertations
Developed two permittivity profile extraction algorithms for inhomogeneous materials. These two algorithms were created using discrete and continuous approaches. The discrete method used a piece-wise constant permittivity assumption that allowed the use of homogeneous wave equations. Using laboratory data and a theoretical formulation, the permittivity of each piece-wise constant layer within the material was extracted using a root search algorithm. The continuous approach solved the problem using inhomogeneous wave equations. These equations were used to extract a linear permittivity profile using laboratory data and a root search.
Silicon Carbide Capacitive High Temperature Mems Strain Transducer, Richard P. Weisenberger
Silicon Carbide Capacitive High Temperature Mems Strain Transducer, Richard P. Weisenberger
Theses and Dissertations
Air Force Research Lab Air Vehicles directorate performs research on hypersonic vehicles. To verify materials or designs of hypersonic vehicles, they have a need to measure strain at temperatures exceeding 700°C. Strain sensors have the ability to measure strain. Strain is the deformation of materials due to internal stresses in a material. Internal stresses occur when a material is subjected to a force. Traditional strain sensors use Piezoresistive effects to measure strain, which is temperature dependent and making them unusable at high temperatures. This paper discusses a novel strain sensing device, sensing capacitance instead of piezoresistance. The strain sensor is …
Local Histograms For Per-Pixel Classification, Melody L. Massar
Local Histograms For Per-Pixel Classification, Melody L. Massar
Theses and Dissertations
We introduce a rigorous mathematical theory for the analysis of local histograms, and study how they interact with textures that can be modeled as occlusions of simpler components. We first show how local histograms can be computed as a system of convolutions and discuss some basic local histogram properties. We then introduce a probabilistic, occlusion-based model for textures and formally demonstrate that local histogram transforms are natural tools for analyzing the textures produced by our model. Next, we characterize all nonlinear transforms which satisfy the three key properties of local histograms and consider the appropriateness of local histogram features in …
Using Vft As A Constraint For Goal Programming Models: A Case Study For Turkish Air Force Flying Hour Program, Ahmet Bengoz
Using Vft As A Constraint For Goal Programming Models: A Case Study For Turkish Air Force Flying Hour Program, Ahmet Bengoz
Theses and Dissertations
In its 60-year history, there have been many published documents in the literature about goal programming (GP), but contributions to the literature are still needed. This research intends to add to the literature on goal-programming models by discussing one of the key assumptions of GP regarding linearity, and by discussing some of the issues regarding incommensurability (difference in data types) and weighting. GP requires an interaction between the decision maker (DM) and the analyst to ensure that the model reflects the DM's preferences. However, it may be difficult for them to interact if the mathematical model is very large and …
Using Hybrid Simulation/Analytical Queueing Networks To Capacitate Usaf Air Mobility Command Passenger Terminals, Meredithe A. Jessup Ii
Using Hybrid Simulation/Analytical Queueing Networks To Capacitate Usaf Air Mobility Command Passenger Terminals, Meredithe A. Jessup Ii
Theses and Dissertations
The objective of this study is to model operations at an airport passenger terminal to determine the optimal service capacities at each station given estimated passenger flow patterns and service rates. The central formulation is an open Jackson queueing network that can be applied to any USAF Air Mobility Command (AMC) terminal regardless of passenger type mix and flow data. A complete methodology for analyzing passenger flows and queue performance of a single flight is produced and then embedded in a framework to analyze the same for multiple departing flights. Queueing network analysis (QNA) is used because no special software …
Analysis Of Kc-46 Live-Fire Risk Mitigation Program Testing, Chad N. Chamberlain
Analysis Of Kc-46 Live-Fire Risk Mitigation Program Testing, Chad N. Chamberlain
Theses and Dissertations
Increased emphasis from the Director of Operational Test and Evaluation (DOT&E) over the past few years to include statistical rigor in all testing has brought an augmented look at testing across the Department of Defense. This thesis examines the methodology currently used in live fire testing, particularly in the case of risk mitigation of the KC-46 dry-bay fire test program. The thesis addresses gaps within the methodology and analyzes the results of a statistically rigorous test. The research furthers work on modeling the characterization of ballistic impact flash by validating concurrent models and characterizing the errors prone to these models …
A Prototype Overview For Allocating Usaid Foreign Aid, Deane E. Cover
A Prototype Overview For Allocating Usaid Foreign Aid, Deane E. Cover
Theses and Dissertations
The United States Agency for International Development (USAID) is the federal government agency primarily responsible for administering civilian foreign aid. In fiscal year 2011, USAID spent approximately $15 billion in an effort to assist countries recovering from disaster, trying to escape poverty, and engaging in democratic reforms. Using Value-Focused Thinking, regression, and optimization techniques, this thesis utilizes overarching USAID objectives and underlying policy to develop a prototype overview model that is used to provide insight to a Decision Maker regarding how changes in funding allocation can lead to improved impact.
Ballistic Flash Characterization: Penetration And Back-Face Flash, Michael J. Koslow
Ballistic Flash Characterization: Penetration And Back-Face Flash, Michael J. Koslow
Theses and Dissertations
The Air Force is extremely concerned with the safety of its people, especially those who are flying aircraft. Aircrew members flying combat missions are concerned with the chance that a fragment from an exploding threat device may penetrate into the airframe to possibly ignite a fire onboard the aircraft. One concern for vulnerability revolves around a flash that may occur when a projectile strikes and penetrates an aircraft's fuselage. When certain fired rounds strike the airframe, they break into fragments called spall. Spall and other fragmentation from an impact often gain enough thermal energy to oxidize the materials involved. This …
A Simulation To Evaluate Joint Military Logistics In A Humanitarian Assistance Environment, Ryan S. Fisher
A Simulation To Evaluate Joint Military Logistics In A Humanitarian Assistance Environment, Ryan S. Fisher
Theses and Dissertations
Currently, no capability exists to cost-effectively simulate and measure a Joint Task Force-Port Opening (JTF-PO) operation to predict cargo throughput based on the availability of resources. The purpose of this research is to create a decision model using Arena® simulation software to provide United States Transportation Command (USTRANSCOM) decision makers the ability to predict cargo throughput in a Humanitarian Assistance/Disaster Response (HA/DR) scenario. The data used in this simulation were taken from the JTF-PO involvement in Operation UNIFIED RESPONSE, Port-au-Prince, Haiti 2010. The research uses a design of experiments approach to statistically plan and measure the throughput of cargo based …
Electro-Luminescent Area Illumination Device, Michael E. Miller, Ronald S. Cok
Electro-Luminescent Area Illumination Device, Michael E. Miller, Ronald S. Cok
AFIT Patents
An electro-luminescent area illumination device that includes two or more area emitters formed on a substrate. Each of the two or more area emitters emit light having different area illumination profiles.
Maintenance Operations Degradation Of Airfield Pavement Markings, John C. Jaszkowiak
Maintenance Operations Degradation Of Airfield Pavement Markings, John C. Jaszkowiak
Theses and Dissertations
Pavement markings are an essential element in the navigational aids subsystem for any airfield. Most airfields still use waterborne paint as the primary marking material, although there are other materials in use on roadways that airfield managers could use to save time and money. An airfield experiences a host of maintenance operations that cause degradation of the pavement markings. Of particular concern are rubber removal operations, sweeping operations, and snowplowing operations. This research focuses on chemical rubber removal operations and sweeping operations. The study evaluates waterborne paint markings and thermoplastic marking strips to determine if these marking materials perform differently …
Plume Characterization Of Busek 600w Hall Thruster, Duc Minh Bui
Plume Characterization Of Busek 600w Hall Thruster, Duc Minh Bui
Theses and Dissertations
The BHT-600W thruster has a high potential to place on various commercial and military satellites as a main propulsion system for orbit maintenance and orbit maneuvering. Therefore, the thruster's performance characteristics and parameters were evaluated for various operating conditions. These parameters include thrust, power consumption, mass flow rate, and efficiencies. Various plume properties were measured and characterized for the thruster to include exhaust beam profile and ion species distribution. The faraday probe was used to examine the thruster plume current density while the ion species fractions were determined by the ExB probe. The inverted pendulum thrust stand was also utilized …
A Programmable Liquid Collimator For Both Coded Aperture Adaptive Imaging And Multiplexed Compton Scatter Tomography, Jack G. M. Fitzgerald
A Programmable Liquid Collimator For Both Coded Aperture Adaptive Imaging And Multiplexed Compton Scatter Tomography, Jack G. M. Fitzgerald
Theses and Dissertations
A novel, fully reconfigurable collimator device for gamma-ray and X-ray imaging was built and tested as a coded aperture. The device consisted of 10x10, 5x5x5 mm3 chambers. Each chamber either was filled with an attenuating liquid, stopping photons, or evacuated of the attenuating liquid, allowing the photons to pass through. As the pattern of on and off chambers was manipulated, different, semi-independent views of the gamma-ray source were found. Noise in reconstructed images decreased in all tests. Image reconstruction was performed with correlation methods and Maximum Likelihood Expectation Maximization (ML-EM). Using 10 mask patterns, the signal-to-noise ratio (SNR) in …
Agent Based Modeling And Simulation Framework For Supply Chain Risk Management, Tiffany J. Harper
Agent Based Modeling And Simulation Framework For Supply Chain Risk Management, Tiffany J. Harper
Theses and Dissertations
This research develops a flexible agent-based modeling and simulation (ABMS) framework for supply chain risk management with significant enhancements to standard ABMS methods and supply chain risk modeling. Our framework starts with the use of software agents to gather and process input data for use in our simulation model. For our simulation model, we extend an existing mathematical framework for discrete event simulation (DES) to ABMS and then implement the concepts of variable resolution modeling from the DES domain to ABMS and provide further guidelines for aggregation and disaggregation of supply chain models. Existing supply chain risk management research focuses …
Sparsening Filter Design For Iterative Soft-Input Soft-Output Detectors, Raquel G. Machado, Andrew G. Klein, Richard K. Martin
Sparsening Filter Design For Iterative Soft-Input Soft-Output Detectors, Raquel G. Machado, Andrew G. Klein, Richard K. Martin
Faculty Publications
A large body of research exists around the idea of channel shortening, where a prefilter is designed to reduce the effective channel impulse response to some smaller number of contiguous taps. This idea was originally conceived to reduce the complexity of Viterbi-based maximum-likelihood equalizers. Here, we consider a generalization of channel shortening which we term "channel sparsening". In this case, a prefilter is designed to reduce the effective channel to a small number of nonzero taps which do not need to be contiguous. When used in combination with belief-propagation-based maximum a posteriori (MAP) detectors, an analogous complexity reduction can be …
Modeling Small Unmanned Aerial System Mishaps Using Logistics Regression And Artificial Neural Networks, Sean E. Wolf
Modeling Small Unmanned Aerial System Mishaps Using Logistics Regression And Artificial Neural Networks, Sean E. Wolf
Theses and Dissertations
A dataset of 854 small unmanned aerial system (SUAS) flight experiments from 2005-2009 is analyzed to determine significant factors that contribute to mishaps. The data from 29 airframes of different designs and technology readiness levels were aggregated. 20 measured parameters from each flight experiment are investigated, including wind speed, pilot experience, number of prior flights, pilot currency, etc. Outcomes of failures (loss of flight data) and damage (injury to airframe) are classified by logistic regression modeling and artificial neural network analysis. From the analysis, it can be concluded that SUAS damage is a random event that cannot be predicted with …
Electroluminescent Area Illumination With Integrated Mechanical Switch, Ronald S. Cok, Michael E. Miller
Electroluminescent Area Illumination With Integrated Mechanical Switch, Ronald S. Cok, Michael E. Miller
AFIT Patents
An electroluminescent lam including a lamp substrate; a first electrode formed over the lamp substrate device side, one or more layers having light-emitting material formed over the first electrode, and a second electrode formed over the one or more layers, a chiplet having a chiplet substrate separate and independent from the lamp substrate and adhered to the lamp substrate device side, one or more connection pads, a mechanical switch, and a control circuit for controlling the mechanical switch, the mechanical switch electrically connected to one or more connection pads and at least one connection pad electrically connected to the first …
The Effect Of Elevated Temperature On The Inelastic Deformation Behavior Of Pmr-15 Solid Polymer, Chad E. C. Ryther
The Effect Of Elevated Temperature On The Inelastic Deformation Behavior Of Pmr-15 Solid Polymer, Chad E. C. Ryther
Theses and Dissertations
The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at temperatures in the 274-316°C range. The experimental program was developed to explore the influence of temperature on tensile loading, relaxation and creep behaviors of PMR-15. The results demonstrate that the mechanical behavior of PMR-15 exhibits a strong dependence on temperature. During strain-controlled tensile loading, the slope of the stress-strain curve in the quasi-elastic region decreases and the flow stress level decreases with increasing temperature. During relaxation, the amount of the stress drop decreases with increasing temperature. Based on experimental results the Viscoplasticity Based on Overstress …
Method For Converting An Input Color Signal, Ronald S. Cok, Michael E. Miller
Method For Converting An Input Color Signal, Ronald S. Cok, Michael E. Miller
AFIT Patents
A white light-emitting microcavity light-emitting diode device, comprising a method for converting a red, green, and blue (RGB) input signal to a converted signal having RGB color signals and an additional saturated color signal, by calculating saturation of the additional saturated color in the RGB input signal to determine the proportion of the additional saturated color signal to the sum of the converted RGB color signals such that the proportion of the additional saturated color signal is constant or decreases as the saturation of the additional color in the RGB input signal increases.
Stereoscopic Display System With Flexible Rendering Of Disparity Map According To The Stereoscopic Fusing Capability Of The Observer, Elaine W. Jin, Michael E. Miller, Serguei Endrikhovski, Cathleen D. Cerosaletti
Stereoscopic Display System With Flexible Rendering Of Disparity Map According To The Stereoscopic Fusing Capability Of The Observer, Elaine W. Jin, Michael E. Miller, Serguei Endrikhovski, Cathleen D. Cerosaletti
AFIT Patents
A method is provided for customizing scene content, according to a user or a cluster of users, for a given stereoscopic display, including obtaining customization information about the user; obtaining a scene disparity map for a pair of given stereo images and/or a three-dimensional (3D) computer graphic model; and determining an aim disparity range for the user. The method of the present invention also generates a customized disparity map and/or rendering conditions for a three-dimensional (3D) computer graphic model correlating with the user's fusing capability of the given stereoscopic display; and renders or re-renders the stereo images for subsequent display.
Afit Graduate School Of Engineering And Management Catalog 2012-2013, Graduate School Of Engineering And Management, Air Force Institute Of Technology
Afit Graduate School Of Engineering And Management Catalog 2012-2013, Graduate School Of Engineering And Management, Air Force Institute Of Technology
AFIT Documents
The Graduate Catalog represents the offerings, programs, and requirements in effect at the time of publication.
Large Aircraft Infrared Countermeasures (Laircm) Systems Engineering Case Study, Air Force Center For Systems Engineering, William Albery
Large Aircraft Infrared Countermeasures (Laircm) Systems Engineering Case Study, Air Force Center For Systems Engineering, William Albery
AFIT Documents
No abstract provided.
Exploitation Of Unintentional Information Leakage From Integrated Circuits, William E. Cobb
Exploitation Of Unintentional Information Leakage From Integrated Circuits, William E. Cobb
Theses and Dissertations
Unintentional electromagnetic emissions are used to recognize or verify the identity of a unique integrated circuit (IC) based on fabrication process-induced variations in a manner analogous to biometric human identification. The effectiveness of the technique is demonstrated through an extensive empirical study, with results presented indicating correct device identification success rates of greater than 99:5%, and average verification equal error rates (EERs) of less than 0:05% for 40 near-identical devices. The proposed approach is suitable for security applications involving commodity commercial ICs, with substantial cost and scalability advantages over existing approaches. A systematic leakage mapping methodology is also proposed to …
Internal Electric Fields Due To Piezoelectric And Spontaneous Polarizations In Cdzno/Mgzno Quantum Well, H. C. Jeon, S. J. Lee, Tae Won Kang, S. H. Park, Yung Kee Yeo, T. F. George
Internal Electric Fields Due To Piezoelectric And Spontaneous Polarizations In Cdzno/Mgzno Quantum Well, H. C. Jeon, S. J. Lee, Tae Won Kang, S. H. Park, Yung Kee Yeo, T. F. George
Faculty Publications
We have investigated optical properties as a function of internal and external fields in the quantum well (QW). Optical properties of CdZnO/MgZnO QW structures are investigated by using many‐body effects. The CdZnO/MgZnO QW structure with high Cd composition is found to have smaller optical gain because the strain‐induced piezoelectric polarization and the spontaneous polarization in the well increase with the inclusion of Cd. These results demonstrate that high performance laser diode operation can be realized in CdZnO/MgZnO QW structures by reducing those polarizations adopting dipole reverse method.